Why Partial First Ray Amputations In Patients With Diabetic Neuropathy Do Not Work

Diabetes mellitus with peripheral sensory neuropathy and the associated increased risk of ulceration continue to be growing issues in today’s society.1-28 Peak ambulatory forces occur about the first ray, creating a cycle of stresses, tissue buildup and eventual breakdown.2 Conservative therapies often fail due to an inability to offload the wound properly, poor pedal hygiene and inadequate distal blood flow. Many of these patients eventually progress to require an amputation.3

Adherence to basic principles requires the removal of all necrotic, non-viable tissue and will result in a functional, durable, residual foot. Preserving the length and integrity of the remaining structures routinely leads to a partial first ray amputation. However, this level of amputation often leads to frequent failures and the need for further intervention, causing us to question the durability and predictability of the partial first ray amputation.

What Two Studies On Partial First Ray Amputation Reveal

We conducted two studies, the first being a systematic review of the world literature to determine the re-amputation rate following a partial first ray amputation in this specific population.4 Of the 435 partial first ray amputations, the incidence of re-amputation was 19.8 percent (86/435). The end stage, most proximal level of amputations following a partial first ray amputation were: an additional digit amputation in 32 patients (37 percent); transmetatarsal amputation in 28 patients (34 percent); and below-knee amputation in 25 patients (29 percent).

The results of this study therefore demonstrate that one of five patients having any version of a partial first ray amputation will eventually require more proximal re-amputation.4 We concluded that, according to the world literature completely from diabetic foot care centers of excellence, partial first ray amputation for patients with diabetes and peripheral sensory neuropathy does not represent a durable, functional or predictable foot-sparing amputation.

Unfortunately, most practitioners are not employed at diabetic foot care centers of excellence. Accordingly, we believe that the incidence of re-amputation for this patient population is likely higher when community-based practitioners perform the amputations. Additionally, little data was available for comparison in regard to morbidity and mortality associated with this procedure.

Therefore, in order to investigate these concerns further, we conducted a retrospective review focusing on patients with diabetes mellitus and peripheral sensory neuropathy who had a partial first ray amputation at the Gundersen Health System over an 11-year period.5 This is a level II trauma, community-based and tertiary referral center in the Midwest.

In this second study, we evaluated a total of 7,487 cases from January 2001 to December 2011 for possible inclusion in the study.5 Of these, 59 patients met the inclusion criteria of diabetes mellitus with peripheral sensory neuropathy and a primary partial first ray amputation. We defined the partial first ray amputation as occurring distal to the first metatarsocuneiform joint, including the phalanges of the hallux, with primary closure at the time of surgery. For this study, we excluded patients if they had additional digital amputation, required vascular intervention or were diagnosed with non-reconstructable ischemic disease. We collected retrospective chart review information to acquire a better understanding of the morbidity and mortality of this procedure in a high-risk population. At the time of the final chart review, 28 of the patients were deceased at a mean of 34.6 months post-initial amputation.

The initial level of amputation is detailed in the chart at right. Healing of the surgical incision occurred in all 59 patients.5 However, 69 percent (41 patients) went on to develop a foot ulceration following the index amputation in a mean of only 10.5 months with an average of 3.1 ulcerations per patient. Additionally, 36 percent (21 patients) required ancillary surgical procedures. There was a mean of 26.6 clinical visits per patient from the time of initial amputation to when either complete healing had occurred with no further ulcerations or definitive re-amputation occurred. In addition, 92 percent of patients took prescription antibiotics postoperatively with a mean of 2.3 different antibiotics prescribed. Unfortunately, 25 (42.4 percent) patients had a more proximal re-amputation within a short mean of 25 months. Interestingly, the most common level of re-amputation did not occur more proximally within the first ray.

Our data determined that in a community-based hospital setting, half of the patients with diabetes and peripheral sensory neuropathy undergoing any version of a partial first ray amputation will eventually require more proximal re-amputation.5 This data questions the reliability and durability of this level of amputation as a primary procedure in this patient population. Additionally, it does not seem fiscally sound.

Final Thoughts

The goal of any amputation is the complete eradication of non-viable tissue, optimizing the host’s healing potential while reducing the risk for further breakdown and the need for extended local wound care, specialized shoe gear or repeated surgical intervention.4 As we demonstrated in the aforementioned studies, a partial first ray amputation at any level in patients with diabetic neuropathy does not meet these goals in this high-risk population in which risk management is especially critical.4 Even a partial hallux amputation had the same potential for re-amputation as a near complete first ray amputation. This implies the significant role the first ray has in the function of the foot and limited tolerance for amputation at this level in insensate feet.

As we noted in the second study, nearly half of these patients will require a more proximal level of re-amputation within a mean of 25 months. There was also a high mortality rate within this patient population with 48 percent of the patients deceased at a mean time of 34.6 months following the index amputation. While one may attribute this to the disease process itself, the mean age of included patients was only 67 years old. Due diligence is therefore required when evaluating the patient to determine the optimal level of initial amputation and may require a more proximal level.3-13

Further, after review of our studies, it may be in the patient’s best interest to get a referral to a more specialized diabetic foot center of excellence since the incidence of re-amputation is half of what results when the patient receives care in a community-based facility. The exact reason for this remains a matter for conjecture since the same multidisciplinary team members (i.e., internal medicine/endocrinologists, infectious disease, vascular surgery, nutritionists, etc.) are present in both settings studied. Further study to elucidate this apparent discrepancy (including non-hospital based private practitioner outcomes) is warranted.

Given the stated goals of surgical intervention, one should not consider any level of amputation that results in the need for further ongoing treatment for re-ulceration with weekly clinical evaluations, local wound management and oral antibiotic therapy as a successful outcome even in the situation of initial healing. In addition to concerns over limb- and life-threatening infection developing, healthcare costs associated with repeated clinical debridement, wound dressings and oral antibiotics are high. Patient satisfaction in the setting of complicated and time consuming dressings and intolerance of prolonged oral antibiotic therapy is also poor.

In light of this, one may consider a single definitive and predictable procedure (such as a primary transmetatarsal amputation) at the time of initial intervention to be more satisfactory to the patient overall.29 Proper patient education is required at the time of surgical consultation to allow for proper decision making in this regard. In addition, one should consider surgical correction of any related foot deformities, such as hammering of the lesser digits, to prevent future ulcerations.30,31

Dr. Borkosky is a graduate with distinction of the Rearfoot/Ankle Surgery Residency at the Gundersen Health System in La Crosse, Wis. She is in private practice at the Palmetto Podiatry Group in Andersen, S.C. Dr. Borkosky is an Associate of the American College of Foot and Ankle Surgeons.

Dr. Roukis is attending staff in the Department of Orthopaedics, Podiatry and Sports Medicine at Gundersen Healthcare System in La Crosse, Wis. He is the President-Elect and a Fellow of the American College of Foot and Ankle Surgeons.

Comments

This is an interesting paper. However, I do take exception to the notion that sub-total 1st ray amputations "don't work." Of course, they work. The issue is highly patient dependent. Certainly, further amputations or revisions do occur and statistically this may exceed what would be acceptable in most scientific reviews.

However, two issues come to mind.

1) What would a "center of excellence" propose? TMA, Chopart disarticulation, or higher amputations to obviate any further foot procedures? (This is assuming that amputation of something is absolutely necessary. I work at two wound centers and certainly SOME recommended amputations can be avoided at times.)

2) Not all the patients fall into the study criteria. For example, my patient in the hospital right now had a sub-total first ray amputation with the 2nd toe disarticulation at the 2nd MTPJ due to overt gangrene, abscess and cellulitis, with a history of severe cardiomyopathy, CKD, s/p ilio-tib bypass, and poorly controlled type 2 diabetes without primary closure of the surgical site. He may have a year to live.

So the final point is sometimes a sub-total first ray amputation DOES work for the particular patient in mind. That's my problem with the title of the paper in that others may reject the necessary procedure.

Please e-mail me any desired response but I do appreciate your efforts in this study.

I currently am the assistant director of a wound care center/limb salvage program. I am called upon to perform partial first ray amputations on a regular basis. I would tend to believe that the destabilization of the forefoot and midfoot after the procedure leads to recurrence and re-amputation at a higher level.

For this reason, I have began "beaming" the remainder of the medial column. I have found initially this prevents the destabilization and further surgical intervention on the first ray and medial column. The patients are followed with a custom insole to help protect the area. Any additional procedures on the lesser digits can be performed assuming appropriate revascularization has been done if needed.

To date, this seems to result in a higher patient satisfaction than a primary transmetatarsal amputation